静态内部类单例缓存地区

package com.qingxing.ManagerComplex.api.util; import org.springframework.jdbc.core.JdbcTemplate; import org.springframework.web.context.WebApplicationContext; import org.springframework.web.context.request.RequestContextHolder; import org.springframework.web.context.request.ServletRequestAttributes; import org.springframework.web.context.support.WebApplicationContextUtils; import javax.servlet.http.HttpServletRequest; import java.util.HashMap; import java.util.List; import java.util.Map; /** * Created by lcc on 2017/8/23. */ public class AreaMapSingleton { public Map<String, Object> AreaMap = null; private AreaMapSingleton() { HttpServletRequest request = ((ServletRequestAttributes) RequestContextHolder .getRequestAttributes()).getRequest(); WebApplicationContext ctx = WebApplicationContextUtils.getWebApplicationContext(request.getServletContext()); JdbcTemplate jdbcTemplate = ctx.getBean(JdbcTemplate.class); String sql = "select t.short_code, t.province,t.city,t.district from tb_ks_areas_all t where t.short_code like '33%' and length(t.short_code) <= '6' "; List<Map<String, Object>> areamaplist = jdbcTemplate.queryForList(sql); Map<String, Object> maps = new HashMap<String, Object>(); for (Map<String, Object> map : areamaplist) { Object fullName = ""; String shortCode = (String) map.get("short_code"); if (shortCode.length() == 2) { fullName = map.get("province"); } else if (shortCode.length() == 4) { fullName = map.get("city"); } else if (shortCode.length() == 6) { fullName = map.get("district"); } maps.put(shortCode, fullName); } AreaMap = maps; } public static Map<String, Object> getAreaMap() { return getInstance().AreaMap; } public static AreaMapSingleton getInstance() { return Nested.instance; } static class Nested { private static AreaMapSingleton instance = new AreaMapSingleton(); } }

需要缓存地区放入map中，静态内部类单例